The assumption of continuity of mineralisation between sampling points, as stated in the JORC Code, requires a “confident interpretation of the geological framework”. The elements of relevance to a geological framework vary greatly depending on the commodity and style of mineralisation. In general terms, at least two elements must be considered to underpin a geological framework: space and time.

The geometry and location of a mineralised body are controlled by physical and/or chemical elements, which can be unravelled by detailed geological mapping, adequate geochemical (including a quality analysis-quality control program) and structural interpretations, and by 3D geological modelling. These elements may involve, among other, aspects of stratigraphy, chemical or physical properties of the rocks (e.g. texture, grain size) and structural features such as faults, fractures and folds.

Mineralisation events that lead to economic deposits are often relatively short-lived periods of focused fluid transfer and element- exchange, which result in mobilisation and deposition of metals in well-defined areas. Understanding the temporal framework and interaction of structural elements and mineralising events (determining genetic relationships, e.g. pre-, syn- and post-mineralisation) results in the development of more accurate geological models and can lead to predictive capabilities and new discoveries.

We present case studies in regional metamorphic, igneous, sedimentary and surficial geological environments, demonstrating how understanding the mineralisation system not only results in increased confidence in the resource, but also facilitates reduction of exploration risks.

Feature Author

Bert De Waele has over 23 years of structural mapping experience, mostly in African Precambrian terranes. In addition, he has consulted on base metal and gold prospects, setting up and running exploration programmes or interpreting regional geochemical data. With SRK, Bert has also conducted Independent Technical Assessments on various mineral assets including gold, porphyry copper, iron ore, manganese, diamond, mineral sands, phosphate, evaporite and uranium. His research interests focus on regional geology and tectonics, by integrating field and laboratory work, including U-Pb microprobe geochronology, isotope (147Sm-144Nd and 87Rb-86Sr) and whole-rock geochemistry and Geographic Information Systems. Bert has a strong commitment to transfer of knowledge, holding an Adjunct Research posting at The University of Western Australia. Bert has taught structural geology, computing in geoscience (GIS - Remote Sensing and DPA (Geosoft)) and supervised field classes, mapping projects and theses (BSc, MSc and PhD) both in French-speaking and English-speaking environments.

Michael has over 15 years’ experience as a geologist. He completed a PhD in post-Variscan tectonics (Ireland) and later completed two years of postdoctoral research into evaluating and modelling active oceanic slope processes. Mike has also worked in both Irish and British civil services where he was involved in shallow seabed mapping, GIS and software development. Mike’s experience with SRK includes projects in Australia and overseas (Indonesia, Lao, Sri Lanka, Kyrgyzstan, Mongolia, Tanzania, Congo, Liberia and Malaysia), and on a variety of commodities including graphite, gold, uranium, iron and potash. He has conducted 3D modelling of vein, epithermal and banded iron formation styles of mineralisation,m and Mineral Resource and exploration target estimates in accordance with JORC Code (2012) reporting guidelines.